1. Field of the Invention
This invention relates generally to a semicondutor laser device and more particularly, to the structure of resonator facets.
2. Description of the Prior Art
Coating of a light emitting output facet of a semiconductor laser device has been primarily directed to prevent facet erosin in the past. Recently, attempts have been made to raise the refractive index by use of a multi-layered film on one side and to reduce the refractive index on one side. However, these attempts provide merely the advantages that the differential quantum efficiency can be improved and the limit of the optical output that can be taken out can be increased.
The following references can be cited to show the state of art.
(1) Applied Physics Letters, Vol. 30, No. 2, 15 January, 1977, p 87-88 PA0 (2) Applied Optics, Vol. 10, No. 7, July, 1971, p 1591-1596 PA0 (3) IEEE JOURNAL OF QUANTUM ELECTRONICS, Vol. QE-17, No. 9, September, 1981, p 1950-1954